
There are over 30 distinct genres of Metal, each one with its own unique culture, style, musical sound and themes. Here is a quick guide to understanding your most basic types of metal music.
Black Metal
The Look:

Quick Summary:
When you hear parental groups or your local priest complaining about too much Satan in metal music, they are usually talking about this genre.
Black Metal emerged in Norway in the early 90s and is characterized by strong double-kick drumming techniques, loud, shrieking, generally impossible to understand vocals and often anti-Christian ideology. With its ties to church burnings and various Nazi movements, Black Metal is probably the least commercial genre in the Metal Music Spectrum.
Rules of Black Metal:
1. No Poofters!
2. Be dark!
3. SATAN!
4. Regular cold cream is the best foundation for your pancake necro anti-Christian make-up.
5. EVIL!
Notable Bands:
Bathory, Burzum, Mayhem, Immortal, Gorgoroth, Emperor
Example of Music:
Death Metal
The Look:

Quick Summary:
Emerging somewhere in the 1980s, Death Metal is often confused with Black Metal due to both genres making use of theatrics, growling vocals and dark themes in their lyrics. However, Death Metal is foremost about technical playing and brutality, compared to Black Metal's emotional and evil style of music. Death Metal growls are also a lot easier to understand than Black Metal shrieks, though both genres have not really been popular with mainstream audiences.
Rules of Death Metal:
1. Brutality! Guts! Blooooooood!
2. No Poofters!
3. Every genre beside death metal is gay (see rule no 2)
4. P00r sp3lling is Br00tal!
5. It is acceptable for Death Metal band members to get really fat.
Notable Bands:
Death, Cannibal Corpse, Dethklok
Example of Music:
Glam Metal
The Look:

Quick Summary:
In the 1980s in Los Angeles (no surprise here), the flamboyant Glam movement has sunk its well polished and glitter covered teeth into Metal Music, combining frizzled hair, lipstick and power rock ballads to create what most know as Hair Metal. If you ever saw something which could kinda be mistaken for metal (in a dark room) on early MTV, chances are it was some Glam Metal band.
The bands of this genre aim to write music with catchy rythms to it and thus produced a great big number of power ballads. Also, did we mention all the coke assosiated with Glam Metal?
Rules of Glam Metal:
1. No Poofters!
2. There is no such thing as too much coke.
3. Scoring with less than 6213 rabid groupies a year makes you gay.
4. Not that there is anything wrong with that.
5. If people can still make you out under that mascara and eyeliner you did not use enough of it.
Notable Bands:
Motley Crue, Twisted Sister, W.A.S.P.
Example of Music:
Nu Metal
The Look:

Quick Summary:
What happens when the new generation wants to listen to metal but without everything that ever made it good, adding lots of angst, DJs, rapping and synth? You get the most schizo genre of music in history, derogatively called "Nu Metal", a type of Metal combining elements of grunge, alternative, funk, industrial and hip hop music. There is an on going theory that Nu Metal was developed by the goverment who pick out anyone who seriously enjoys it and silently eradicates them because their minds have obviously went sour.
Rules of Nu Metal:
1. There are No rules!
2. Like, "Make music that is good" - not in the Nu Metal rule book;
3. You are even allowed to rap.
4. Or hell, bring on DJs, who are known for being metal.
5. No Poofters!
Notable Bands:
Korn, Linkin Park, Mushroomhead
Example of Music:
Power Metal
The Look:

Quick Summary:
Characterized by extremely clean and high vocals as if the singer had yet to reach puberty, Power Metal has its roots in symphonic music and fantasy literature. Its lyrics often deal with mythology, singing about magical lands, mythical creatures and sometimes personal struggles. Power Metal is considered the least manly genre of Metal. It is the nerdy kid in glasses who wears a cape to school and spends all his free time in a basement playing table top RPGs with his equally socially inept friends.
Incidentally, Power Metal is also one of the most technically proficient types of Metal.
Rules of Power Metal:
1. Be Epic!
2. Thus, it is acceptable to sing about your latest D&D campaign.
3. Best Power Metal vocalists have singing voices virtually identical to women.
4. No Poofters!
5. Though it is OK to dress like them.
Notable Bands:
Blind Guardian, Helloween, Sonata Arctica, Kamelot
Example of Music:
Thrash Metal
The Look:

Quick Summary:
Thrash is the original bad boy of metal and grandpappy to the Black and Death varieties of the music. If it's extreme, fast, aggressive and you can mostly understand what the hell they are singing about, chances are you are listening to Thrash. In the 1980s, Thrash, with its Big Four (Anthrax, Metallica, Megadeth and Slayer), brought the entire heavy metal phenomenon to the public's doorstep, then it set the public's doormat on fire and made a whicked guitar riff right in their face. The public tried calling the police but they were powerless against the extreme power of Thrash Metal.
Rules of Thrash Metal:
1. No Poofters!
2. Never smile.
3. Be angry. But not evil. That's for those black metal queers.
4. No Poofters!
5. Proficient playing is for queers (see rules 1 and 4)
Notable Bands:
Anthrax, Megadeth, Slayer, Metallica
Example of Music:
Doom Metal: Funeral Parlor metal
Folk Metal: Black or Power metal with violin
Gothic Metal: If Hot Topic was a gender of music
Industrial Metal: High School shop class noises pretending to be music
Metalcore: Purposely unrefined sound of punk meets loudness of metal
Neo-classical Metal: Self counscious metal who wants to be serious and respected but is hated by all
Progressive Metal: When Music School kids make metal
Speed Metal: Metal which is faster than regular metal
Stoner Metal: What happens when you and your friends get together to play Guitar Hero
Level 80 Elite Tauren Chieftan - Metal for WoW Geeks

A Blizzard in-house band which performs in World of Warcraft. Previously known as Level 60 and 70 Elite Taurent Chieftans. More previously known as people with girlfriends.
Stovokor - Klingon Death Metal

A Portland death metal band whose members firmly believe they are Klingons, and never appear publically without their plastic foreheads. They sing primarily in the made up language of Klingon.
Bolt Thrower - Metal for Table Top RPG Nerds

A British death metal band who sings mainly about war, and what is more war-y than Warhammer, the popular table top fantasy game? The band also takes inspiration from Warhammer's SF equivalent, Warhammer 40 000.
Admonish - Christian Black Metal aka Unblack Metal

One of the first Christian Black Metal bands, a genre usually assosiated with anti-Christianity, Satan and burning churches. 2 of Admonish's members have appeared on Pimp my Ride.
Cracked Talk on | Metal Music
Shame on listing notable Death Metal bands and forgetting about Morbid Angel and Deicide but listing Dethklok, who not only don't play death metal but aren't even a real band.
Very well put together, this is owning those other topics
Someone doesn't like metal haha. Ahh sucks though I like Progressive and Nu-metal. Like Slipknot and Mudvayne...Then ya got the old school like Pantera Metallica and such. Still though, I find even people who like metal are super picky and prejudiced about other genres of metal. I hate glam and power. It just doesn't do it for me. And what about bands like Black Label Society?